This weekend marks the 50th anniversary of the adoption of the American Standard Code for Information Interchange (ASCII) as a standard for federal computers, an effort by President Lyndon B. Johnson to help ensure compatibility in rapidly developing computer technology.
In the 1960s computers were powerful tools, but they often were still standalone tools, direct descendants of one-off computers developed during World War II to help break enemy codes and compute artillery firing tables. Twenty years later computers were faster and more versatile, and mass production and standardization was making them more affordable and user friendly. But fully unlocking the potential of this technology required interoperability and the ability to communicate with each other (and with us), and this required standards.
This was the purpose of LBJ’s March 11, 1968, memorandum on ASCII. “All computers and related equipment configurations brought into the Federal Government inventory on and after July 1, 1969, must have the capability to use the Standard Code for Information Interchange and the formats prescribed by the magnetic tape and paper tape standards when these media are used.”
Covering the basics
ASCII originally was a scheme for encoding the characters of the Latin alphabet, Arabic numerals and English punctuation, as well as commands for printing and transmission. It called for a 7-bit character code (seven 0s and 1s to represent each character or command) when adopted in 1963 by the American Standards Association (now the American National Standards Institute). An additional bit was later added to accommodate additional characters and commands.
This common standard for representing letters and numbers paved the way for such tools as e-mail, the first killer app of the Internet. According to the Engineering and Technology History Wiki (ETHW) ASCII was the most common character encoding scheme used on the Web as late as 2007 and still is in common use today.
President Johnson called the adoption of ASCII “a major step toward minimizing costly incompatibility among our vast Federal computer and telecommunications data systems.”
Evolving role
Although it has played a major role in computer communications, ASCII was not developed specifically for computers. Again according to the ETHW, it was first used commercially by teletype machines using the AT&T Teletypewriter eXchange network.
Teletype output using ASCII could be printed in a human-readable form on paper and also encoded on paper tape for digital typesetting. As its uses grew ASCII was expanded to include additional characters and commands. In the original scheme the first 32 codes were non-printed commands and the next 96 were the original collection of printable characters. When ASCII expanded to 8-bit encoding another 128 codes were made available so that the character sets and commands could be adapted to more alphabets, operating systems and programs.
Each character for command is designated by a decimal number, which is expressed for computers in binary form. The character “A” is the decimal 065, which is expressed in binary as 01000001. Lowercase “a” is 097, expressed 01100001.
“This effort brought about an agreement on standards used across telecommunication and computer industries,” ETHW said in citing ASCII as a technology milestone. ASCII has been largely superseded today by UTF-8, a variable width character encoding scheme in which ASCII lives on in the first 128 symbols.
The emergence of this standard for digital communication and its adoption by the federal government proved a boon for both the tech industry and national security. It provided a technical backbone for the National Communications System, originally established after the 1962 Cuban Missile Crisis to provide fast, reliable communications within the U.S. government and with its allies and adversaries.
“The standard code will be used as the basic code in those networks of the National Communications System whose primary function is either the transmission of record communications or the transmission of data related to information processing,” Johnson’s 1968 memo directed.
A special thanks to Bobbi Jackson, C-SPAN Radio’s resident historian and LBJ expert, for pointing out this anniversary.